Updated: As responders continue searching for more survivors in the decimated remains of a Texas fertilizer plant and its surrounding neighborhood after a Wednesday night explosion, authorities have recovered 12 bodies and say more than 200 people were injured by the blast, according to the Associated Press and Fox News.

In a Friday briefing, U.S. Sen. John Cornyn (R-Texas) said 60 people are still unaccounted for, USA Today reports.

Meanwhile, as multiple federal and state agencies investigate the cause of the disaster, which apparently started with a fire that set off heat-sensitive fertilizer or another chemical, the regulatory framework in which the West fertilizer plant operated in the midst of a small farming community is being scrutinized.

A lengthy Bloomberg article says the plant was last inspected by the Occupational Safety and Health Administration in 1985. (OSHA is now sending inspectors to the plant to see if there are any violations.) And an emergency management plan filed with the Environmental Protection Agency said there was no risk of fire or explosion, only a possible brief release of ammonia gas that posed no major health hazard.

In addition to the liquid fertilizer that reportedly is believed to have caused the explosion, the plant also was storing solid ammonium nitrate at the end of 2012, the Waco Tribune reports.

Used for fertilizer as well as bombs, ammonium nitrate was the cause of an industrial explosion at a Texas City plant that killed more than 580 people on April 18, 1947, the newspaper says.

An owner and a general manager at the West plant did not respond Thursday to phone messages from the Waco Tribune seeking comment.